Field of the Invention (Technical Field)
The presently claimed invention relates to oil and gas equipment, and more particularly to an apparatus and method to block or prevent debris, chemicals, and sand from entering the internal body cavity of hydraulic fracturing (fracking or frac) equipment and valves.
Background Art
In the oil and gas industry there is a practice called fracking, to speed up the migration of gas and petroleum fluid from source rocks or reservoir rocks. This is a process where high pressure pumps and powerful engines pump sand, water and/or chemicals through high pressure flow lines, valves, and equipment that are attached to fracking devices known in the industry as a frac valve, frac stack or frac equipment, hereinafter referred to collectively as a frac valve. A frac valve can be configured in many different sizes and pressure ratings. Each design is usually specific to the user's application and requirements. Frac valves are attached to a wellhead that is attached to a high-pressure pipe that can extend thousands of feet into the ground and cemented into gas or oil formations. These devices are attached to the wellhead by bolting or other well-known means of fastening and are tightened to a predetermined torque by hydraulics or hammer tools.
The fracking process requires high pressure pumps to push the fracturing fluids, including proppants, a material such as grains of sand, ceramic, or other particulates, that prevent the fractures from closing when the injection is stopped, into the injected fluid and chemicals through the frac valves for several hours or days; depending on the amount of proppants and fluids required to be injected into the ground at high pressures, and velocity to break up and create cracks in the formation.
A typical frac valve 10 is shown in FIG. 1. During the fracking process, abrasive proppants, fluids, and chemicals 12 are able to flow 14 through the bores of frac valve 10 at high pressures and high velocities and into the casing wellbore and finally into the formation. During this process, cavities 16 of frac valve 10 also allows proppants 12 to pass into the valve body cavity 16, an area or void behind the mechanical moving parts. This allows the injection fluid to travel into the valve bore cavity and fill with debris 18, such as the frac sands and chemicals. Once the chemicals and sand work their way into the cavities and bores, or spaces between parts, which are required for any moving part to function properly, many problems occur that cause the equipment to wear, malfunction, fail or become inoperable. This can cause a dangerous situation to life and/or the environment.
A typical frac valve 10 as shown in FIG. 1, is used to contain and shut off pressure to perform special or specific functions during a frac operation by opening and closing gate 20, by raising to allow the flow or lowering to stop the flow, by means of a hand operated wheel or by means of air or hydraulic actuators. The high pressure is sealed off by closing the gate during or after the fracturing operation. There are many points in the current design of frac valves 10, which still require improvements despite the fact that the known frac valves have been commercially successful and have lessened dangers in operation.
First, frac valves 10 and other associated high-pressure valves must be operated under or with high pressure. Additionally, sometimes frac valves 10 require high torque to force the gate opened and closed at high pressures that are pressing against the open or closed gate 20 of the frac valve 10. Typical prior art frac stack valves 10 fill with debris 18 during the fracturing process by debris leaking through the connection between the gate and the valve aperture, and may not allow valve gate 20 to fully open or close, creating a dangerous or unsafe environment.
While frac stack valves 10 and fittings have tightly controlled inside and outside parameters, there must be looser tolerances in order for a frac valve gate 20 to travel in and out of the valve body cavity 16. Accordingly, due to these loose tolerances, gate 20 cannot properly seal against or seat on one or both sides of gate 20 during the open position and one side during the closed position. Conversely, the tolerances and packing or seal may fit loosely against the gate face but may be too loose and thus, susceptible to permitting proppant chemical or debris to enter valve body cavity 16 during the fracturing process. This causes operational problems, which include the inability to fully close gate 20, to fully open gate 20, or damage to the seal surface of gate 20, by corrosion, washed seats or the like.
Presently, attempts to solve this problem include pumping heavy and expensive greases or sealants in the bore or cavities in order to prevent or block pathways by installation of devices or springs that apply force against the parts to limit the tolerances. The shortcomings of injecting special greases or sealants fails to prevent the problems of debris collection, corrosion, and the injection must be repeated each time a valve is cycled. Therefore, there is a need for an apparatus and method for effectively blocking the pathways for debris entering a valve body cavity during a fracking operation without jeopardizing the normal operation of the valve.